In 2018, I saw a project that offered solutions to a similar problem. Now I do not remember what it was called, but I will try to describe its essence.
Let's say you have an encrypted message or file on the blockchain. In which all the keys from different projects are stored and instructions for working with them. At your choice: for example, once a month you will receive a letter in your mail to which you need to answer with the necessary password within 1 month. If you have not responded within a month, the file with the keys is sent to your relative, to the mail previously indicated by you.